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Unformatted text preview: 1 Proteins, Amino Acids & Us Water accounts for 60-70% of our body weight, followed by amino acids (proteins) with 20%. Thus, a person weighing 50 kg consists of about 10 kg of proteins, which make up important tissues of the body such as muscles, gastrointestinal tract, internal organs, hemoglobin in the blood, and the collagen of our hair and skin. The constituents of these proteins are amino acids. Outline of lecture topics... Essential amino acids Limiting amino acids Improving protein quality Basic protein structure Protein function(s) & enzymes Protein quality What are the Protein Building Blocks -Amino Acids So, amino acid s are composed of: An acid part An amino part And another part R There are 20 common R parts that are different and make the differences among the amino acids Occasionally, you find extra oddball amino acids C COOH I H I R H 2 N Many theories have been presented to explain the origin of life: In many cases, however, amino acids are said to be the source of life. Some meteorites which collided with the earth after a long journey from the remotest corner of the universe contain amino acids. Trace amounts of glycine, alanine, and glutamate, and were detected in a meteorite that struck Murchison (Australia) in 1969. The amino acids in meteorites are considered a trace of life elsewhere in the universe. A trilobite fossil dating back to 500 million years ago was found to contain amino acids such as alanine. Science continues its search for an answer to the intriguing mystery of the origin of life by studying the amino acids detected in fossils and meteorites. 2 Scientific history of aa s In 1806 an amino acid was first discovered from asparagus shoots in France, and was named asparagine. After this, cysteine, glycine, and leucine were found from urinary calculus, gelatin, and muscles/wool, respectively. All the protein-constituting amino acids were discovered by 1935. In 1908 Dr. Kikunae Ikeda (Japan) discovered that glutamate is the Umami component of sea tangle. After amino acids were found to be responsible for the secret of deliciousness, the various properties of amino acids were studied in Japan in great depth. Dietary need for amino acids About 500 kinds of amino acids have been discovered in nature. However, only 20 amino acids serve as the constituents of our body proteins Complicated combinations of these 20 kinds produce more than 100 thousand kinds of proteins. When we eat food such as meat, fish, and cereals, the proteins contained in it are first degraded to the 20 kinds of amino acids, and then reassembled into proteins in the body....
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This note was uploaded on 01/31/2012 for the course FST 10 taught by Professor Jack during the Summer '08 term at UC Davis.
- Summer '08